Biogas and biomethane are an important means to delivering a sustainable, low carbon energy future. Renewable energy targets have driven significant growth in the biogas economy, as biomethane can be used in existing transmission networks and within vehicles. EN 16723 specifies gas quality recommendations for these uses.
NPL provides traceable high accuracy gas mixtures for biogas and biomethane analysis and offers gas quality testing services. Mixtures and testing services containing additional components not listed on this page may also be available on request.
Multi-component standards are available, including, but not limited to the components and ranges in the table below. UKAS accreditation to ISO 17034 and ISO 17025 is available for the ranges in the table below.
Component |
Amount fraction range
|
Uncertainty
|
| Nitrogen | 1 - 25 | 0.3 - 0.5 |
| Methane | 35 - 99.9 | 0.1 - 0.2 |
| Carbon dioxide | 0.04 - 55 | 0.1 - 0.5 |
| Ethane | 0.0020 – 0.5000 | 0.42 - 1.0 |
| Propane | 0.0020 – 0.5000 | 0.4 - 1.0 |
| Oxygen | 0.2 – 1.5 | 0.3 - 1.0 |
| Hydrogen | 0.2 – 3 | 0.4 - 1.0 |
Raw biogas contains a diverse range of impurities, which vary in amount fraction depending on the source material used. European standards EN 16723-1 and EN16723-2 specify maximum limit values for impurities found within upgraded biogas and biomethane. NPL’s gas reference standards are being used to directly support the development of the biogas economy.
Siloxane impurities within biogas cause damage to processing equipment when combusted, even at trace-levels. NPL offers traceable gas standards containing the most common siloxanes found in biogas. The table below provides amount fraction ranges and uncertainties NPL offers.
Component |
Amount fraction range (µmol/mol) |
Silicon mass fraction
|
Relative Uncertainty (%) |
Matrix |
| L2 (Hexamethyldisiloxane) | 0.004 – 3000 | 0.010 - 7127 | 2 - 10 |
|
| L3 (Octamethyltrisiloxane) | 0.004 – 300 | 0.014 - 1069 | 2 - 10 | |
| D3 (Hexamethylcyclotrisiloxane) | 0.004 – 700 | 0.014 - 2494 | 2 - 10 | |
| D4 (Octamethylcyclotetrasiloxane) | 0.004 – 100 | 0.019 - 475 | 2 – 10 | |
| D5 (Decamethylcyclopentasiloxane) | 0.004 – 10 | 0.024 – 59 | 5 - 15 |
Depending on the nature of the substrate, the anaerobic digestion process produces sulphur-containing compounds ranging from ppb levels to several thousands of ppm. NPL offers traceable reference standards of binary and multi-component sulphur compounds within biogas. UKAS accreditation is available for matrices of methane and nitrogen.
Component |
Amount fraction range (µmol/mol) |
Relative Uncertainty (%) |
Matrix |
| Hydrogen sulphide | 0.4 to 5000 | 2 - 5 |
Biogas, Methane or Nitrogen |
| Carbonyl sulphide | 0.4 to 5000 | 2 - 5 | |
| Carbon disulphide | 0.4 to 200 | 2 - 5 | |
| Dimethyl sulphide | 0.4 to 200 | 2 - 5 | |
| Ethyl methyl sulphide | 0.4 to 200 | 2 - 5 | |
| Diethyl sulphide | 0.4 to 200 | 2 - 5 | |
| Methanethiol | 0.4 to 200 | 2 - 5 | |
| Ethanethiol | 0.4 to 200 | 2 - 5 | |
| 2-propanethiol | 0.4 to 200 | 2 - 5 | |
| 1-propanethiol | 0.4 to 200 | 2 - 5 | |
| 2-methyl-2-propanethiol | 0.4 to 200 | 2 - 5 | |
| Tetrahydrothiophene | 0.4 to 200 | 2 - 5 |
Terpenes are a common impurity found within biogas due to the nature of the biological source material. The presence of trace level terpenes within biomethane cause the scent of typical sulphur odorant additives to be masked, posing a health and safety risk. In addition they are capable of causing degradation of polymeric seal materials used within transmission grid pipelines. NPL provides reference standards containing terpenes within biogas, methane and nitrogen matrices.
Component |
Amount fraction range (µmol/mol) |
Relative Uncertainty (%) |
Matrix |
| (+/-)-α-pinene | 0.01-10 | 2 - 5 |
Biogas, Methane or Nitrogen |
| (+/-)-β-pinene | 0.01-10 | 2 - 5 | |
| (+)-3-carene | 0.01-10 | 2 - 5 | |
| 1,8-cineole (eucalyptol) | 0.01-10 | 2 - 5 | |
| Limonene | 0.01-10 | 2 - 5 | |
| Isoprene | 0.01-10 | 2 - 5 |
Benzene, toluene, ethylbenzene and xylenes are volatile mono-aromatic hydrocarbons found within biogas. NPL provides reference standards containing terpenes within biogas, methane and nitrogen matrices.
Component |
Amount fraction range (nmol/mol) |
Relative Uncertainty (%) |
Matrix |
| Benzene | 500 - 2000 | 2 - 5 |
Biogas, Methane or Nitrogen |
| Toluene | 500 - 2000 | 2 - 5 | |
| Ethylbenzene | 500 - 2000 | 2 - 5 | |
| m+p-xylene | 500 - 2000 | 2 - 5 | |
| o-xylene | 500 - 2000 | 2 - 5 |
Ammonia is produced during the anaerobic digestion process and is found within biogas. NPL provides reference standards containing ammonia within biogas, methane and nitrogen matrices.
Component |
Amount fraction range (nmol/mol) |
Relative Uncertainty (%) |
Matrix |
| Ammonia | 10 - 1000 | 5 - 10 |
Biogas, Methane or Nitrogen |
NPL offers biomethane purity testing services against our traceable primary reference materials. Please contact us for more information using the option at the bottom of the page.
NPL offers ‘on-demand’ proficiency testing schemes for biogas and biomethane composition and impurities. Please contact us for more information using the option at the bottom of the page.
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